t5he one you will be used to is for a double socket. the one he's referring to is slightly wider with a divider and inboard lugs so as to accept 2 single sockets side by side. reason for using 2 singles is that a single socket is rated 20A whweas a double is 20A total for both sides.Thanks for your help I will do that but I can’t understand the difference between this dual pattrass and double socket
see pic.